1. Field of the Invention
This invention relates to lifting devices, and, more particularly, to a hydraulic vehicle lift which is capable of lifting an end of a contemporary automobile either by an adjacent pair of wheels, or by a "dead" type axle supporting the wheels, without damaging the autmobile with the upright axle-forks of the lift when the vehicle is lifted by the wheels.
2. Description of the Prior Art
In the past, hydraulic vehicle lifts were developed to permit a person to conveniently work beneath a vehicle. A conventional hydraulic lift included a operating head, mounted atop an extensible hydraulic ram. Two operating-head-supporting rams were often used to lift the respective ends of the vehicle.
To serve in the common situation of on-going use of the lift to consistently service a particular type of vehicle, lifts with fixed-position lifting surfaces were commonly employed. To allow service access to the vehicle, with the wheels, connected axle assembly and supporting springs either loaded or unloaded, a dual-mode operating head for a hydraulic lift was developed. The dual-mode head presented alternate sets of fixed-lifting surfaces. The dual-mode head included a ram-mounted set of forks for meeting and lifting the axle of the vehicle, and also included a set of wheel saddles for alternately lifting the vehicle by the wheels. A shifting mechanism allowed a set of yokes, or sockets, to be shifted to either of two positions. In the first position, the yokes could be engaged for lifting the vehicle with the wheel saddles. In the second position, the yokes would be bypassed and the axle forks could pass through the plane of the wheel saddles and thus lift the vehicle by the axle.
Recently, popular, mass-produced automobiles have utilized a "dead" type rear axle. Being physically smaller than the tranditional "live" type driving rear axle, a smaller space was required to mount the axle beneath the vehicle, and a more efficient utilization of interior space was allowed. However, a problem arose, because the dual-mode hydraulic vehicle lifts of the past were built to operate in the larger axle openings which had been previously commonly used. When used to lift a "dead" type axle vehicle, the protrusion of the axle forks beyond the upper surface of the wheel saddle, combined with the preexisting compression of the suspension springs, caused contact of the axle forks against the lower surface of the vehicle chassis.
The resulting damage was an expensive problem. A need continued to exist for a fork-equipped, dual-mode, operating head for a hydraulic vehicle lift, which operating head would permit the vehicle to be lifted by the wheels without causing fork-damage to the lower surfaces of the vehicle.